Human life vs Animal life

[Banefull]

It seems to be one of the biggest philosophical problems on these boards as evdienced by many of the arguments going on in various threads. Most of the arguments have been over single issues but we should perhaps address the overall question -- At what point does animal life take precedence over human life?

Just to highlight the scope of the issue, look at these questions:

If a pack of wolves is attacking a human, can I kill all of the wolves?
If wolves often attack humans, can I eradicate the several thousand wolves living in the area?
i.e. What is the cut-off point between saving human life and saving animal life?

If a bear is breaking into my car can I shoot it?
i.e. Can I kill animals to protect my property?

If blackbirds are eating my crops can I poison them?
i.e. Can I kill animals to protect my livelihood?

If a deer is crippled, can I shoot it to put it out of its misery?
i.e. Euthanasia on animals?

If a fly is buzzing around my house, can I take a flyswatter and smack it?
i.e. Can I kill animals so I can be more comfortable?

The questions are endless but it shows the scope of the dilemna. What are everyone's thoughts?